linux/fs/btrfs/async-thread.h
Chris Mason 4e3f9c5042 Btrfs: keep irqs on more often in the worker threads
The btrfs worker thread spinlock was being used both for the
queueing of IO and for the processing of ordered events.

The ordered events never happen from end_io handlers, and so they
don't need to use the _irq version of spinlocks.  This adds a
dedicated lock to the ordered lists so they don't have to run
with irqs off.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-11 13:31:04 -04:00

116 lines
3.6 KiB
C

/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#ifndef __BTRFS_ASYNC_THREAD_
#define __BTRFS_ASYNC_THREAD_
struct btrfs_worker_thread;
/*
* This is similar to a workqueue, but it is meant to spread the operations
* across all available cpus instead of just the CPU that was used to
* queue the work. There is also some batching introduced to try and
* cut down on context switches.
*
* By default threads are added on demand up to 2 * the number of cpus.
* Changing struct btrfs_workers->max_workers is one way to prevent
* demand creation of kthreads.
*
* the basic model of these worker threads is to embed a btrfs_work
* structure in your own data struct, and use container_of in a
* work function to get back to your data struct.
*/
struct btrfs_work {
/*
* func should be set to the function you want called
* your work struct is passed as the only arg
*
* ordered_func must be set for work sent to an ordered work queue,
* and it is called to complete a given work item in the same
* order they were sent to the queue.
*/
void (*func)(struct btrfs_work *work);
void (*ordered_func)(struct btrfs_work *work);
void (*ordered_free)(struct btrfs_work *work);
/*
* flags should be set to zero. It is used to make sure the
* struct is only inserted once into the list.
*/
unsigned long flags;
/* don't touch these */
struct btrfs_worker_thread *worker;
struct list_head list;
struct list_head order_list;
};
struct btrfs_workers {
/* current number of running workers */
int num_workers;
/* max number of workers allowed. changed by btrfs_start_workers */
int max_workers;
/* once a worker has this many requests or fewer, it is idle */
int idle_thresh;
/* force completions in the order they were queued */
int ordered;
/* more workers required, but in an interrupt handler */
int atomic_start_pending;
/*
* are we allowed to sleep while starting workers or are we required
* to start them at a later time?
*/
int atomic_worker_start;
/* list with all the work threads. The workers on the idle thread
* may be actively servicing jobs, but they haven't yet hit the
* idle thresh limit above.
*/
struct list_head worker_list;
struct list_head idle_list;
/*
* when operating in ordered mode, this maintains the list
* of work items waiting for completion
*/
struct list_head order_list;
struct list_head prio_order_list;
/* lock for finding the next worker thread to queue on */
spinlock_t lock;
/* lock for the ordered lists */
spinlock_t order_lock;
/* extra name for this worker, used for current->name */
char *name;
};
int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work);
int btrfs_start_workers(struct btrfs_workers *workers, int num_workers);
int btrfs_stop_workers(struct btrfs_workers *workers);
void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max);
int btrfs_requeue_work(struct btrfs_work *work);
void btrfs_set_work_high_prio(struct btrfs_work *work);
#endif